The conversion of compact gasoline spark ignition engines to diesel or heavy-fuels operated engines for various applications requiring miniaturized power sources, including robotics and exoskeleton, and small scale propulsion system, forces a series of adaptation of the current off-the-shelf engines. These adaptations allow a conventional miniaturized gasoline engine to be fueled by heavy-fuels at the expense of significant inefficiencies. Most of these diesel operated gasoline engines have serious ignition difficulties, especially at sub-zero temperatures, and generally show poor performance with respect to the actual power available for energy extraction from the fuel. Furthermore, increased fuel consumption with production of heavy smoke and pollutant emissions, and several other negative factors, severely penalizes the adoption of these modified engines. The need for air-breathing small-scale propulsion systems, with high power densities for civilian and military applications is ever increasing. The objective of the present invention is to provide a small-scale hybrid-engine (SSHE) formed by the integration of several technologies allowing its miniaturization without impairing the overall engine efficiency.
A secondary objective of the proposed invention is that of providing a wearable power source equipped with its own fuel tank, pumps, starter mechanisms, mufflers, injectors, etc. This wearable, or mobile, SSHE system can deliver a minimum of 20 W average for prolonged amounts of time with minimum fuel consumption, and load following characteristics. SSHE can also produce a scalable power output able to achieve and exceed this minimum power requirement so that it can serve multiple applications. Such applications may require a power source for power hungry systems such as microclimate cooling with power requirements in excess of 1200 W-hr, or able to provide shaft power for actuators used for robotic applications, or as a propulsion system for remotely controlled vehicles. Load following characteristics imply a rigorous control of the various combustion parameters forcing a fast response on the rotating components of the burner. All components are designed for minimum weight and bulk. Components like miniaturized compressor and exhaust gases wheels impose high degrees of manufactory accuracy and complexity. All of the components of this invention can function in a wide range of temperatures and environments, including submerged in water, while resisting to shocks derived from mechanical impacts or explosions. The complete system is reliable and damage-tolerant, posing no hazards to the operator.
To meet these requirements, technology has been pushed beyond its current limits and the integration of several innovative concepts produced the SSHE. Every ounce of mass of the SSHE system contributes to performance, and every watt generated, thermal, electrical, or mechanical is applied with the highest conversion efficiency. These are the main objectives of the SSHE proposed as a miniaturized power source utilizing fossil fuels.